External heat exchanger for stoves

ABSTRACT

A heat exchanger takes existing hot gases from a stove exit and removes heat from these hot exhaust gases. The heat exchanger makes the stove more efficient. The exhaust gases may go through a conductive material core, such as an aluminum core, where forced air passing through pipes through the heat exchanger warms up by radiation, conduction and convection.

BACKGROUND OF THE INVENTION

The present invention relates to heating systems and, more particularly, to an external heat exchanger for pellet, wood or gas stoves.

Normally, hot gas is just vented into the atmosphere. The efficiency of a stove, such as a pellet, wood or gas stove, may be substantially reduced due to the loss of heat into the atmosphere of exhaust gas.

As can be seen, there is a need for an apparatus for reclaiming heat from the hot exhaust gas from a stove.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a heat exchanger comprises a heat exchanger core, the heat exchanger core forms, in one embodiment, a U-shape; an intake pipe adapted to receive exhaust gas from a stove into the heat exchanger core; an exhaust pipe adapted to receive exhaust gas exiting from the heat exchanger core; a plurality of pipes passing through the heat exchanger core; an intake plenum delivering air into the plurality of pipes; and an output plenum receiving air from the plurality of pipes.

In another aspect of the present invention, a heat exchanger comprises an intake pipe adapted to receive exhaust gas from a stove into, in one embodiment, a U-shaped heat exchanger core; an exhaust pipe adapted to receive exhaust gas exiting from the heat exchanger core; a plurality of pipes passing through the heat exchanger core; an intake plenum delivering air into the plurality of pipes; an output plenum receiving air from the plurality of pipes; a fan to force air into the intake plenum; a plurality of spacers attached to a shell of the heat exchanger core; and an outer shell attached to the plurality of spacers.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a heat exchanger according to an exemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view of the heat exchanger of FIG. 1, taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view of the heat exchanger of FIG. 1, taken along line 3-3 of FIG. 1; and

FIG. 4 is a cross-sectional view of the heat exchanger of FIG. 1, taken along line 4-4 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Various inventive features are described below that can each be used independently of one another or in combination with other features.

Broadly, an embodiment of the present invention provides a heat exchanger that takes existing hot gases from the stove exit and removes heat from these hot exhaust gases. The heat exchanger makes the stove more efficient. The exhaust gases may go through a metal or sufficient core, such as an aluminum core, where forced air passing on the external surface of the heat exchanger warms up by radiation, conduction and convection. This intervention increases the efficiency of a heat source, i.e. a stove, including but not limited to pellet, wood or gas stoves, which will substantially increase efficiency due to the recapture of heat that normally vented as exhaust gas.

Referring to FIGS. 1 through 4, a heat exchanger 10 may receive exhaust gases from a stove, such as a wood stove, a pellet stove, a gas stove, or the like through an intake pipe 12. The exhaust gases may pass through a core 15 of the heat exchanger 10 in the direction of the arrows of FIG. 1. The exhaust gases may exit the heat exchanger 10 through an exhaust pipe 14. In some embodiments, the intake pipe 12 and the exhaust pipe 14 may be aligned such that a straight pipe may connect from the stove outlet (not shown, where the intake pipe 12 of the heat exchanger attaches) to a venting pipe (where the exhaust pipe 14 of the heat exchanger connects) when the heat exchanger 10 is not present.

An inner core shell 22 may deflect the incoming exhaust gases to direct the exhaust gases through the core 15. The core 15 may be made of, for example, aluminum, or some other highly heat conductive material. The heat exchanger 10 may be sized to be disposed, for example, between the exit flue of a stove (not shown) and existing ductwork that passes through a wall. The heat exchanger 10 may be in a bent/straight or U-shape as shown in FIG. 1 to permit maximum heat exchange surface area while permitting the heat exchanger 10 to be located in a relatively small space.

A core shell 18 may form an inside surface of the core 15. A plurality of spacers 20 may separate an outer shell 16 from the core shell 18. The outer shell 16 may provide a shroud for safety, limiting the external surface temperature of the heat exchanger 10.

A plurality of tubes 24 may pass through the core 15 of the heat exchanger 10. The tubes 24 may be, for example, thin-walled, round aluminum tubes. Air may be passed through the tubes 24 to remove heat from the exhaust gases. A fan 26 may be used to force air into an intake plenum 28. The intake plenum 28 is in fluid contact with each of the plurality of the tubes 24. The air is passed through the tubes 24 to gain heat from the exhaust gases and the air is then exited into an exit plenum 30. From the exit plenum 30, the air may be forced back into the room as warmed air. The tubes 24 may pass substantially perpendicular or angled to increase heat exchange rate of exhaust gas through the heat exchanger 10. The warmed air exiting the exit plenum 30 may be optionally ducted into a forced air heating system or other ducting to deliver the warmed air to a desired location.

The air from the intake plenum 28 may also pass through the space formed between the core shell 18 and the outer shell 16. This design may further help keep the external surface of the heat exchanger 10 cool to the touch.

The intake pipe 12 and the exhaust pipe 14 may be sized to fit the stove's design. For example, the pipes 12, 14 may be 3 inch round pipe, 4 inch round pipe, 6 inch round pipe, 8 inch round pipe, 10 inch round pipe, or the like.

The heat exchanger of the present invention may be able to extract useful heat from hot exhaust gas from stoves, making them more efficient. This increased efficiency is achieved without any additional pollutants.

To install the heat exchanger of the present invention, a user may simply remove the stove pipe disposed between the stove and the wall, for example, and place the heat exchanger therebetween. The fan may be powered with standard 110V alternating current. In some embodiments, for example in a pellet stove that has an auxiliary power output, the fan may be powered by this auxiliary power output, thereby only powering the fan when the stove is running.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A heat exchanger comprising: a heat exchanger core, the heat exchanger core formed in a straight, angled or U-shape; an intake pipe adapted to receive exhaust gas from a heat source into the heat exchanger core; an exhaust pipe adapted to receive exhaust gas exiting from the heat exchanger core; a plurality of pipes passing through the heat exchanger core; an intake plenum delivering air into the plurality of pipes; and an output plenum receiving air from the plurality of pipes.
 2. The heat exchanger of claim 1, further comprising a fan to force air into the intake plenum.
 3. The heat exchanger of claim 1, further comprising: a plurality of spacers attached to a shell of the heat exchanger core; and an outer shell attached to the plurality of spacers.
 4. The heat exchanger of claim 3, wherein the intake plenum delivers air between the shell and the outer shell.
 5. The heat exchanger of claim 1, wherein the pipes are round tubes formed from a heat conductive material.
 6. The heat exchanger of claim 1, further comprising an inner core shell adapted to direct the exhaust gas through the heat exchanger core.
 7. The heat exchanger of claim 1, wherein the heat source is a wood stove, a pellet stove or a gas stove.
 8. A heat exchanger comprising: an intake pipe adapted to receive exhaust gas from a stove into a heat exchanger core; an exhaust pipe adapted to receive exhaust gas exiting from the heat exchanger core; a plurality of pipes passing through the heat exchanger core; an intake plenum delivering air into the plurality of pipes; an output plenum receiving air from the plurality of pipes; a fan to force air into the intake plenum; a plurality of spacers attached to a shell of the heat exchanger core; and an outer shell attached to the plurality of spacers.
 9. The heat exchanger of claim 8, wherein the intake plenum is configured to delivers air between the shell and the outer shell.
 10. The heat exchanger of claim 8, wherein the pipes are round tubes formed from a heat conductive material. 